Conventionally, a lamp for vehicles of this type is conventionally known (for example, Patent Literature 1). Hereinafter, a conventional lamp for vehicles will be described. The conventional lamp for vehicles forms an engagingly locking protrusion at a lens holder; forms an engagingly locking hole in a heat sink; and engagingly locks the engagingly locking protrusion with the engagingly locking hole in one direction to thereby attach the lens holder to the heat sink.